This invention relates generally to improvements in polymer-based biological implant materials, such as intraocular lenses designed for implantation into the eye to replace a cataractous natural lens. More particularly, this invention relates to surface passivation of such implant materials or lenses to substantially reduce or eliminate adverse reactions with tissue or cells and further to substantially reduce or eliminate undesirable medical complications and/or patient discomfort.
Intraocular lenses and other biological implant devices formed at least in part from polymeric materials are relatively well known for use in a wide variety of medical implant applications. For example, plastic intraocular lenses are used extensively for implantation into the eye as a replacement for a natural lens which has been surgically removed typically due to opacification, referred to commonly as a cataract condition. Such intraocular lenses have traditionally been formed from polymethyl methacrylate (PMMA) selected for its optical properties and its historically perceived inertness to adverse tissue reaction when implanted into the eye. Other polymeric materials have also been used, such as polypropylene, to form support loops for intraocular lenses or forming other types of implant devices, wherein such materials have also been considered to be relatively inert.
Recent pathological studies have indicated, however, the consistent presence of at least some inflammatory reaction to a polymeric implant particularly with intraocular lenses implanted into the eye in contact or in close proximity with sensitive eye tissues or cells. More particularly, such studies have revealed the presence of a reactive membrane covering the intraocular lens wherein the membrane is formed from proteinaceous material and complex cellular structures commonly including macrophages associated with an irritative or inflammatory reaction. In many instances, these reactive membranes have remained relatively transparent from an optical standpoint and thus have not significantly reduced the clarity of patient vision. In other instances, however, the reactive membranes have transitioned to thicker, scar-like tissue, sometimes accompanied by fibrosis, with varying degrees of opacification resulting in undesirable vision loss.
There exists, therefore, a need for an improved biological implant material particularly for use as an intraocular lens, wherein the material is designed for substantially minimizing or eliminating inflammatory reaction with surrounding tissue or cells. The present invention fulfills this need and provides further related advantages.